linux-toradex.git/tools/testing/selftests/vm, branch v5.15-rc5

selftests: vm: add COW time test for KSM pages

2021-09-03T16:58:18+00:00

Since merged pages are copied every time they need to be modified, the
write access time is different between shared and non-shared pages.  Add
ksm_cow_time() function which evaluates latency of these COW breaks.
First, 4000 pages are allocated and the time, required to modify 1 byte in
every other page, is measured.  After this, the pages are merged into 2000
pairs and in each pair, 1 page is modified (i.e.  they are decoupled) to
detect COW breaks.  The time needed to break COW of merged pages is then
compared with performance of non-shared pages.

The test is run as follows: ./ksm_tests -C
The output:
	Total size:    15 MiB

	Not merged pages:
	Total time:     0.002185489 s
	Average speed:  3202.945 MiB/s

	Merged pages:
	Total time:     0.004386872 s
	Average speed:  1595.670 MiB/s

Link: https://lkml.kernel.org/r/1d03ee0d1b341959d4b61672c6401d498bff5652.1629386192.git.zhansayabagdaulet@gmail.com
Signed-off-by: Zhansaya Bagdauletkyzy 
Reviewed-by: Tyler Hicks 
Reviewed-by: Pavel Tatashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

selftests: vm: add KSM merging time test

2021-09-03T16:58:18+00:00

Patch series "add KSM performance tests", v3.

Extend KSM self tests with a performance benchmark.  These tests are not
part of regular regression testing, as they are mainly intended to be used
by developers making changes to the memory management subsystem.

This patch (of 2):

Add ksm_merge_time() function to determine speed and time needed for
merging.  The total spent time is shown in seconds while speed is in
MiB/s.  User must specify the size of duplicated memory area (in MiB)
before running the test.

The test is run as follows: ./ksm_tests -P -s 100
The output:
	Total size:    100 MiB
	Total time:    0.201106786 s
	Average speed:  497.248 MiB/s

Link: https://lkml.kernel.org/r/cover.1629386192.git.zhansayabagdaulet@gmail.com
Link: https://lkml.kernel.org/r/318b946ac80cc9205c89d0962048378f7ce0705b.1629386192.git.zhansayabagdaulet@gmail.com
Signed-off-by: Zhansaya Bagdauletkyzy 
Reviewed-by: Tyler Hicks 
Reviewed-by: Pavel Tatashin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

selftests: vm: add KSM merging across nodes test

2021-09-03T16:58:18+00:00

Add check_ksm_numa_merge() function to test that pages in different NUMA
nodes are being handled properly.  First, two duplicate pages are
allocated in two separate NUMA nodes using the libnuma library.  Since
there is one unique page in each node, with merge_across_nodes = 0, there
won't be any shared pages.  If merge_across_nodes is set to 1, the pages
will be treated as usual duplicate pages and will be merged.  If NUMA
config is not enabled or the number of NUMA nodes is less than two, then
the test is skipped.  The test is run as follows: ./ksm_tests -N

Link: https://lkml.kernel.org/r/071c17b5b04ebb0dfeba137acc495e5dd9d2a719.1626252248.git.zhansayabagdaulet@gmail.com
Signed-off-by: Zhansaya Bagdauletkyzy 
Reviewed-by: Pavel Tatashin 
Reviewed-by: Tyler Hicks 
Cc: Hugh Dickins 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

selftests: vm: add KSM zero page merging test

2021-09-03T16:58:18+00:00

Add check_ksm_zero_page_merge() function to test that empty pages are
being handled properly.  For this, several zero pages are allocated and
merged using madvise.  If use_zero_pages is enabled, the pages must be
shared with the special kernel zero pages; otherwise, they are merged as
usual duplicate pages.  The test is run as follows: ./ksm_tests -Z

Link: https://lkml.kernel.org/r/6d0caab00d4bdccf5e3791cb95cf6dfd5eb85e45.1626252248.git.zhansayabagdaulet@gmail.com
Signed-off-by: Zhansaya Bagdauletkyzy 
Reviewed-by: Pavel Tatashin 
Reviewed-by: Tyler Hicks 
Cc: Hugh Dickins 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

selftests: vm: add KSM unmerge test

2021-09-03T16:58:18+00:00

Add check_ksm_unmerge() function to verify that KSM is properly unmerging
shared pages.  For this, two duplicate pages are merged first and then
their contents are modified.  Since they are not identical anymore, the
pages must be unmerged and the number of merged pages has to be 0.  The
test is run as follows: ./ksm_tests -U

Link: https://lkml.kernel.org/r/c0f55420440d704d5b094275b4365aa1b2ad46b5.1626252248.git.zhansayabagdaulet@gmail.com
Signed-off-by: Zhansaya Bagdauletkyzy 
Reviewed-by: Pavel Tatashin 
Reviewed-by: Tyler Hicks 
Cc: Hugh Dickins 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

selftests: vm: add KSM merge test

2021-09-03T16:58:18+00:00

Patch series "add KSM selftests".

Introduce selftests to validate the functionality of KSM.  The tests are
run on private anonymous pages.  Since some KSM tunables are modified,
their starting values are saved and restored after testing.  At the start,
run is set to 2 to ensure that only test pages will be merged (we assume
that no applications make madvise syscalls in the background).  If KSM
config not enabled, all tests will be skipped.

This patch (of 4):

Add check_ksm_merge() function to check the basic merging feature of KSM.
First, some number of identical pages are allocated and the MADV_MERGEABLE
advice is given to merge these pages.  Then, pages_shared and
pages_sharing values are compared with the expected numbers using
assert_ksm_pages_count() function.  The number of pages can be changed
using -p option.

Link: https://lkml.kernel.org/r/cover.1626252248.git.zhansayabagdaulet@gmail.com
Link: https://lkml.kernel.org/r/90287685c13300972ea84de93d1f3f900373f9fe.1626252248.git.zhansayabagdaulet@gmail.com
Signed-off-by: Zhansaya Bagdauletkyzy 
Reviewed-by: Pavel Tatashin 
Reviewed-by: Tyler Hicks 
Cc: Shuah Khan 
Cc: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

selftests/vm/userfaultfd: wake after copy failure

2021-09-03T16:58:16+00:00

When userfaultfd copy-ioctl fails since the PTE already exists, an -EEXIST
error is returned and the faulting thread is not woken.  The current
userfaultfd test does not wake the faulting thread in such case.  The
assumption is presumably that another thread set the PTE through copy/wp
ioctl and would wake the faulting thread or that alternatively the fault
handler would realize there is no need to "must_wait" and continue.  This
is not necessarily true.

There is an assumption that the "must_wait" tests in handle_userfault()
are sufficient to provide definitive answer whether the offending PTE is
populated or not.  However, userfaultfd_must_wait() test is lockless.
Consequently, concurrent calls to ptep_modify_prot_start(), for instance,
can clear the PTE and can cause userfaultfd_must_wait() to wrongly assume
it is not populated and a wait is needed.

There are therefore 3 options:
(1) Change the tests to wake on copy failure.
(2) Wake faulting thread unconditionally on zero/copy ioctls before
    returning -EEXIST.
(3) Change the userfaultfd_must_wait() to hold locks.

This patch took the first approach, but the others are valid solutions
with different tradeoffs.

Link: https://lkml.kernel.org/r/20210808020724.1022515-4-namit@vmware.com
Signed-off-by: Nadav Amit 
Cc: Jens Axboe 
Cc: Andrea Arcangeli 
Cc: Peter Xu 
Cc: Alexander Viro 
Cc: Axel Rasmussen 
Cc: Mike Rapoport 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

selftests: Fix spelling mistake "cann't" -> "cannot"

2021-09-03T16:58:13+00:00

There is a spelling mistake in an error message. Fix it.

Link: https://lkml.kernel.org/r/20210826121217.12885-1-colin.king@canonical.com
Signed-off-by: Colin Ian King 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

selftests/vm: use kselftest skip code for skipped tests

2021-09-03T16:58:13+00:00

There are several test cases in the vm directory are still using exit 0
when they need to be skipped.  Use the kselftest framework to skip code
instead so it can help us to distinguish the return status.

Criterion to filter out what should be fixed in vm directory:
  grep -r "exit 0" -B1 | grep -i skip

This change might cause some false-positives if people are running these
test scripts directly and only checking their return codes, which will
change from 0 to 4.  However I think the impact should be small as most of
our scripts here are already using this skip code.  And there will be no
such issue if running them with the kselftest framework.

Link: https://lkml.kernel.org/r/20210823073433.37653-1-po-hsu.lin@canonical.com
Signed-off-by: Po-Hsu Lin 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

selftest: use mmap instead of posix_memalign to allocate memory

2021-07-24T00:43:28+00:00

This test passes pointers obtained from anon_allocate_area to the
userfaultfd and mremap APIs.  This causes a problem if the system
allocator returns tagged pointers because with the tagged address ABI
the kernel rejects tagged addresses passed to these APIs, which would
end up causing the test to fail.  To make this test compatible with such
system allocators, stop using the system allocator to allocate memory in
anon_allocate_area, and instead just use mmap.

Link: https://lkml.kernel.org/r/20210714195437.118982-3-pcc@google.com
Link: https://linux-review.googlesource.com/id/Icac91064fcd923f77a83e8e133f8631c5b8fc241
Fixes: c47174fc362a ("userfaultfd: selftest")
Co-developed-by: Lokesh Gidra 
Signed-off-by: Lokesh Gidra 
Signed-off-by: Peter Collingbourne 
Reviewed-by: Catalin Marinas 
Cc: Vincenzo Frascino 
Cc: Dave Martin 
Cc: Will Deacon 
Cc: Andrea Arcangeli 
Cc: Alistair Delva 
Cc: William McVicker 
Cc: Evgenii Stepanov 
Cc: Mitch Phillips 
Cc: Andrey Konovalov 
Cc: 	[5.4]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds